import {
	Vector4
} from 'three';
import * as NURBSUtils from './NURBSUtils.js';

/**
 * NURBS surface object
 *
 * Implementation is based on (x, y [, z=0 [, w=1]]) control points with w=weight.
 **/

class NURBSSurface {

	constructor(degree1, degree2, knots1, knots2 /* arrays of reals */, controlPoints /* array^2 of Vector(2|3|4) */) {

		this.degree1 = degree1;
		this.degree2 = degree2;
		this.knots1 = knots1;
		this.knots2 = knots2;
		this.controlPoints = [];

		const len1 = knots1.length - degree1 - 1;
		const len2 = knots2.length - degree2 - 1;

		// ensure Vector4 for control points
		for (let i = 0; i < len1; ++i) {

			this.controlPoints[i] = [];

			for (let j = 0; j < len2; ++j) {

				const point = controlPoints[i][j];
				this.controlPoints[i][j] = new Vector4(point.x, point.y, point.z, point.w);

			}

		}

	}

	getPoint(t1, t2, target) {

		const u = this.knots1[0] + t1 * (this.knots1[this.knots1.length - 1] - this.knots1[0]); // linear mapping t1->u
		const v = this.knots2[0] + t2 * (this.knots2[this.knots2.length - 1] - this.knots2[0]); // linear mapping t2->u

		NURBSUtils.calcSurfacePoint(this.degree1, this.degree2, this.knots1, this.knots2, this.controlPoints, u, v, target);

	}

}

export { NURBSSurface };
